The size of the CSS unit Px,em,rem difference

Px

px Pixels (Pixel). Relative length units. Pixel px is relative to the display screen resolution. The use of PX can accurately locate page elements, however, the display of different display pages may vary, more difficult to compatible.

Em

EM is the size of the font that is scaled based on the datum. The EM essence is a relative value, not a specific number. EM is calculated relative to the attributes of the parent element, if the parent element's font-size is 16px,2em=2*16px=32px.

Rem

REM is also a relative value, but REM is calculated relative to the font-size of the HTML root element.

The default font size of the general browser is 16px, the conversion between units convenient, 10÷16=0.625, you can set the HTML font-size for 62.5%,1em=10px,16px=1.6em. Because Chrome has a minimum font size of 12px, this setting eventually gets bigger.

The size of the CSS unit Px,em,rem difference